Please move your gaze around the image, resting from time to time.
Then, fix your gaze at a point, and see what happens.
You will probably first see ‘snakes’ rotating, some clockwise, others anticlockwise, and then stop. In fact, it’s just an stationary image — nothing is moving at all.
Visual perception is created by our brain’s interpretation of visual information. Our minds actively interpret perceptual input, rather than passively record it — make sure to remember that next time you have a disagreement with someone!
On human perception and fruit flies:
Which optical illusions can animals see? (NatGeo):
VISUAL ILLUSIONS REMIND us that we are not passive decoders of reality but active interpreters. Our eyes capture information from the environment, but our brain can play tricks on us. Perception doesn’t always match reality.
Scientists have used illusions for decades to explore the psychological and cognitive processes that underlie human visual perception. More recently, evidence is emerging that suggests many animals, like us, can perceive and create a range of visual illusions…
In an August study in Proceedings of the National Academy of Sciences, for example, Yale researchers showed that fruit flies, like humans, can be fooled into seeing motion in an image where there is none, such as the rotating snake illusion, well-known to neuroscientists and psychologists … The more scientists look—in the lab and in nature—the more similarities they’re finding between how humans and animals perceive the world.
Mechanism for analogous illusory motion perception in flies and humans (PNAS). From the Abstract:
- Significance: Most of the time, visual circuitry in our brains faithfully reports visual scenes. Sometimes, however, it can report motion in images that are in fact stationary, leading us to perceive illusory motion. In this study, we establish that fruit flies, too, perceive motion in the stationary images that evoke illusory motion in humans. Our results demonstrate how this motion illusion in flies is an artifact of the brain’s strategies for efficiently processing motion in natural scenes. Perceptual tests in humans suggest that our brains may employ similar mechanisms for this illusion. This study shows how illusions can provide insight into visual processing mechanisms and principles across phyla.